- a subordinate or accessory part.
- a side branch, as of a blood vessel or nerve.
- collateral circulation.
Origin of collateral
- security pledged for the repayment of a loan
- (as modifier)a collateral loan
Word Origin for collateral
late 14c., "accompanying," also "descended from the same stock," from Old French collateral (13c.), from Medieval Latin collateralis "accompanying," literally "side by side," from Latin com- "together" (see com-) + lateralis "of the side," from latus "a side" (see oblate (n.)). Literal sense of "parallel, along the side of" attested in English from mid-15c. Related: Collaterally.
16c., "colleague, associate," from collateral (adj.). Meaning "thing given as security" is from 1832, American English, from phrase collateral security (1720).